I'm getting tired of keeping a log on gas purchases and guessing what I've got left in the tank. Original gage only registers when I'm about to run out-big help! I don't want to tear into the dash again to replace the gage. I thought I would hook up an after market gage. I have a new sending unit in the tank. So my question is how many ohms are there on full and how many on empty. I need this info to pick a gage that will work with my factory sending unit. Any help would be appreciated.